So God is one, but somehow also three.The fact is difficult to understand,
but it is quite unavoidable in Scripture and central to the gospel.The doctrine of the Trinity attempts to
account for this fact and to exclude heresies that have arisen on the
subject.Its basic assertions are
these: (1) God is one.(2) God is
three.(3) The three persons are
each fully God.(4) Each of the
persons is distinct from the others.(5) The three persons are related to one another eternally as Father,
Son, and Holy Spirit.–John Frame[3]

Importance of Doctrine

For we must always remember that as
we study this fact, we are not dealing with a doctrine about God, with an
abstract concept, or with a scientific proposition about the nature of
Divinity.We are not dealing with
a human construction which we ourselves or which others have put upon the
facts, and which we now try to analyze and logically to dismember.Rather, in treating of the Trinity, we
are dealing with God Himself, with the one and true God, who has revealed
Himself as such in His Word.[4]

--Herman
Bavinck

But to have the “right” answers about the
Trinity, for example, and to actually believe in the reality of the Trinity, is
all the difference in the world.The advantage of believing in the reality of the Trinity is not that we
get an A from God for giving “the right answer.”Remember, to believe something is to act as if it is
so.To believe that two plus two
equals four is to behave accordingly when trying to find out how many dollars
or apples are in the house.The
advantage of believing it is that we can deal much more successfully with
reality.Just try dealing with it
as if two plus two equaled six.

Hence, the advantage of believing in the Trinity is that we then live
as if the Trinity is real: as if the cosmos environing us actually is, beyond
all else, a self-sufficing community of unspeakably magnificent personal beings
of boundless love, knowledge, and power.And, thus believing, our lives naturally integrate themselves, through
our actions, into the reality of such a universe, just as with two plus two
equals four.In faith we rest
ourselves upon the reality of the Trinity in action—and it graciously meets
us.For it is there.And our lives are then enmeshed in the
true world of God.[5]

--Dallas
Willard

The doctrine of the Trinity was formulated
by followers of Jesus Christ to safeguard the good news that in Jesus Christ we
encounter God face to face.It was
not devised to make God less understandable, or to make God so mysterious that
the common people would have to depend on clergy and theologians to understand
it for them as the JWs charge.[6]

--Robert
Bowman

What then is lost from Christian theism,
when we cease to think in trinitarian terms?... The conviction that God is love
is the major casualty of unitarian theism.

…………..

The otherlosses of
non-trinitarian religion are of a piece with this major casualty.Christ becomes one inspired man among
others; and the Spirit a universal divine immanence within creation.We no longer have a living Saviour, by
incorporation into whose Body we too can say ‘Abba, Father’; we no longer can
think of our prayers and worship as taken up into the inner movement of God’s
life.[7]

--Brian
Hebblethwaite

Why was the church so concerned about the doctrine
of the Trinity? Is it really essential to hold to the full deity of the Son and
the Holy Spirit? Yes it is, for this teaching has implications for the very
heart of the Christian faith. First, the atonement is at stake. If Jesus is
merely a created being, and not fully God, then it is hard to see how he, a
creature, could bear the full wrath of God against all of our sins. Could any
creature, no matter how great, really save us? Second, justification by faith
alone is threatened if we deny the full deity of the Son. (This is seen today
in the teaching of the Jehovah’s Witnesses, who do not believe in justification
by faith alone.) If Jesus is not fully God, we would rightly doubt whether we
can really trust him to save us completely. Could we really depend on any
creature fully for our salvation? Third, if Jesus is not infinite God, should
we pray to him or worship him? Who but an infinite, omniscient God could hear
and respond to all the prayers of all God’s people? And who but God himself is
worthy of worship? Indeed, if Jesus is merely a creature, no matter how great,
it would be idolatry to worship him—yet the New Testament commands us to do so
(Phil. 2:9-11; Rev. 5:12-14). Fourth, if
someone teaches that Christ was a created being but nonetheless one who saved us,
then this teaching wrongly begins to attribute credit for salvation to a
creature and not to God himself. But this wrongfully exalts the creature rather
than the Creator, something Scripture never allows us to do. Fifth, the
independence and personal nature of God are at stake: If there is no Trinity,
then there were no interpersonal relationships within the being of God before
creation, and, without personal relationships, it is difficult to see how God
could be genuinely personal or be without the need for a creation to relate to.
Sixth, the unity of the universe is at stake: If there is not perfect plurality
and perfect unity in God himself, then we have no basis for thinking there can
be any ultimate unity among the diverse elements of the universe either.
Clearly, in the doctrine of the Trinity, the heart of the Christian faith is at
stake. Herman Bavinck says that “Athanasius understood better than any of his
contemporaries that Christianity stands or falls with the confession of the
deity of Christ and of the Trinity.”Bavinck, The Doctrine of God p. 281. He adds, “In the confession of the
Trinity throbs the heart of the Christian religion: every error results from,
or upon deeper reflection may be traced to, a wrong view of this doctrine.”Ibid.,
p. 285.[8]

--Wayne Grudem

Trinity in the Old Testament

The Old Testament may be likened to
a chamber richly furnished but dimly lighted; the introduction of light brings
into it nothing which was not in it before; but it brings out into clearer view
much of what is in it but was only dimly or even not at all perceived
before.The mystery of the Trinity
is not revealed in the Old Testament; but the mystery of the Trinity underlies
the Old Testament revelation, and here and there almost comes into view. Thus
the Old Testament revelation of God is not corrected by the fuller revelation
which follows it, but only perfected, extended and enlarged.[9]

--B.
B. Warfield

Trinity in NT as already fully developed

It is clear, in other words, that,
as we read the New Testament, we are not witnessing the birth of a new
conception of God.What we meet
with in its pages is a firmly established conception of God underlying and giving
it tone to the whole fabric.It is
not in a text here and there that the New Testament bears its testimony to the
doctrine of the Trinity.The whole
book is Trinitarian to the core; all its teaching is built on the assumption of
the Trinity; and its allusions to the Trinity are frequent, cursory, easy and
confident…The doctrine of the Trinity does not appear in the New Testament in
the making, but as already made.[10]

--B.
B. Warfield

Experiential Trinitarians

The disciples were, indeed, “experiential
Trinitarians.”They had walked
with the Son, heard the Father speak from glory, and were now indwelt by the
Holy Spirit.[11]--James
White

Problems with Modalism

i.The
cross is emptied of its drama.

Rather, these Fathers clearly understood that what was at stake in this
battle was the authenticity of God’s self-revelation.They understood that if the relationality found throughout
the New Testament between the Father, Son, and the Holy Spirit was something
that God merely assumed in time for the purpose of our salvation, as the
modalists maintained, then even when we come to know God as he truly is.For what God is “truly” like, according
to both ancient modalists and contemporary Oneness believers, lies in the
supposed “undifferentiated Oneness,” which is hidden behind the three (or more)
“masks” he wears in time.

In other words, in Oneness theology the three temporary “roles” of God
do not arise out of God’s essential eternal being.God “plays” Father, Son, and Holy Spirit.But in his heart of hearts—whoever he
is—he is not these three.

The big question, then, was whether the history of salvation was to be
thought of as a sort of stage where God merely acts out certain roles that are
otherwise foreign to his essential self, or whether this history reveals the
innermost heart and internal depth of the eternal and infinite Godhead.Does God simply wear masks before us,
or does he lovingly envelop us into the very depths of his essential and
eternal being?The early Fathers,
thankfully, perceived that the latter was the truth.[12]

ii.Love
between the Father and Son is compromised

Perhaps the most tragic implication of reducing the Father/Son personal
distinction to a mere distinction of natures (or even outright “illusion”) is
that it completely undermines the genuineness of the Father’s personal love for
the Son and the Son’s personal love for the Father spoken of so poignantly
throughout the New Testament.[David] Bernard specifically addresses the issue of this apparent loving
relationship between the Father and the Son when he writes:

John 3:35, 5:20, and 15:9 state that the Father loves the Son [forget
the numerous other texts!], and John 17:24 says the Father loved Jesus before
the foundation of the world.In
John 14:31 Jesus expresses love for the Father [again, one verse!].All of these statements do not mean
separate persons….What these verses express is the relationship between the two
natures of Christ.The Spirit of
Jesus loved the humanity and vice versa….Remember, the Son came to the world to
show us how much God loves us and also to be our example.For these two objectives to be
achieved, the Father and Son showed love for each other.[David Bernard, The Oneness of God: Series in Pentecostal Theology, vol. 1 (1983)]

Greg
Boyd adds:

Therefore, in beholding the love of the Father for the Son and the love
of the Son for the Father, we are not seeing anything that concerns the eternal
heart of God himself.God could
just as well have done without this pseudo-interpersonal “projected” love.Since the two “persons” are projected,
and the love is expressed only for an example, none of this can tell us how God
really is, how God really feels, what God is really like.In the Oneness view, we only know that
God is “absolutely one,” so whatever he is like, he is not like he appears when
the Father and Son are portrayed as distinct and as perfectly loving one
another.And thus in the end the
Incarnation shows us, not what God is (compare John 1:14, 18), not even what
God is like, but only what we human beings should be like![13]